Liquid crystal display device and method of manufacturing the same

ABSTRACT

A liquid crystal display device includes an array substrate, an opposite substrate and a liquid crystal display layer. The array substrate includes a pixel electrode and a lower reactive mesogen layer. The pixel electrode includes a plurality of slit portions disposed on a plurality of domains in different directions. The lower reactive mesogen layer is disposed on the pixel electrode to induce an inclined direction of liquid crystal molecules. The opposite substrate includes an upper substrate. An upper reactive mesogen layer is disposed on a common electrode of the opposite substrate. The liquid crystal layer includes liquid crystal molecules arranged to have a pretilt angle between a surface of the lower reactive mesogen layer and a surface of the upper reactive mesogen layer.

This application claims priority to Korean Patent Application No.2008-106521 filed on Oct. 29, 2008, and all the benefits accruingtherefrom under 35 U.S.C. § 119, the contents of which are hereinincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Exemplary embodiments of the present invention relate to a liquidcrystal display (“LCD”) device and a method of manufacturing the LCDdevice. More particularly, exemplary embodiments of the presentinvention relate to an LCD device capable of enhancing display qualitysuch as a viewing angle and a response speed, and a method ofmanufacturing the LCD device.

2. Description of the Related Art

In a liquid crystal display (“LCD”) device, a voltage is applied to anelectric field generating electrode to provide the liquid crystal layerwith an electric field, and an arrangement of liquid crystal moleculesof the liquid crystal layer is controlled in response to the electricfiled, thereby displaying images.

In order to obtain a high contrast ratio and a wide viewing angle, apatterned vertical alignment (“PVA”) mode LCD device has been developed.In the PVA mode LCD device, an opening portion (hereinafter, a slitportion) of a slit shape is formed through the electric field generatingelectrode, and liquid crystals are vertically aligned to realizemultiple domains.

For a medium or small sized mobile LCD device, in order to decrease theslit portion which decreases an aperture ratio, a micro slit mode LCDdevice or a super patterned vertical alignment (“SPVA”) mode LCD devicehas been developed. In the micro slit mode LCD device, a micro slitportion is only formed through a lower electrode of the electric fieldgenerating electrodes to provide a direction property to the liquidcrystal, and an upper electrode is formed as a flat continuous plate inwhich an opening portion is not formed.

In a vertical alignment (“VA”) mode, such as the PVA mode and the microslit mode, a rubbing is not directly performed on an alignment layer,however, a light alignment method may be employed which aligns liquidcrystal by inducing anisotropy to an alignment layer through lightirradiating.

Polarized UV lights are irradiated to a light bridge high-molecularcopolymer including a mesogenic group of a liquid crystal property, alsocalled a reactive mesogen, to induce anisotropy, and then anisotropy ofthe alignment layer is enhanced to align liquid crystal by heatprocessing on the light bridge high-molecular copolymer.

BRIEF SUMMARY OF THE INVENTION

Since a reactive mesogen may be employed to induce anisotropy to analignment layer through light irradiating, there may be technicaldifficulties in manufacturing an LCD device when the reactive mesogen isused. For example, the reactive mesogen is not cured at a surface of thealignment layer, and the reactive mesogen remains within an inner areaof the liquid crystal layer. The remaining reactive mesogen may beadditionally cured by a backlight of the LCD device, however, the curedamounts of the reactive mesogen in accordance with varying areas aredifferent from each other so that a pretilt angle of liquid crystal maybe non-uniform between the varying areas. As a result, an afterimage maybe undesirably viewed on a display screen.

Exemplary embodiments of the present invention provide an LCD devicehaving improved display quality, such as a viewing angle and a responsespeed.

Exemplary embodiments of the present invention provide a method ofmanufacturing the above-mentioned LCD device.

An exemplary embodiment of an LCD device includes an array substrate, anopposite substrate and a liquid crystal layer. The array substrateincludes a lower substrate, a pixel electrode and a lower reactivemesogen layer. The lower substrate includes a switching part disposedthereon. The pixel electrode is disposed on a unit pixel area of thelower substrate to contact with the switching part. The pixel electrodeincludes a plurality of slit portions disposed on a plurality of domainsand extended in different directions. The lower reactive mesogen layeris disposed on the pixel electrode to induce a slant direction of liquidcrystal molecules. The opposite substrate includes an upper substrateopposite to the lower substrate. A common electrode is disposed on theupper substrate and faces the pixel electrode, and an upper reactivemesogen layer is disposed on the common electrode. The liquid crystallayer includes liquid crystal molecules affected to have a pretilt angleand disposed between a surface of the lower reactive mesogen layer and asurface of the upper reactive mesogen layer.

In an exemplary embodiment of the present invention, the array substratemay further include a lower alignment layer disposed between the pixelelectrode and the lower reactive mesogen layer. The opposite substratemay further include an upper alignment layer disposed between the commonelectrode and the upper reactive mesogen layer. A weight of uncuredreactive mesogen material diffused from the lower and upper reactivemesogen layers to the liquid crystal layer, is no more than about 20weight percent (wt %) with respect to a weight of the lower and upperreactive mesogen layers. The LCD device may further include a diffusionstop layer disposed on surfaces of the lower reactive mesogen layer andthe upper reactive mesogen layer to block the reactive mesogen layerfrom being diffused to the liquid crystal layer.

In an exemplary embodiment of the present invention, the pixel electrodemay include a first pixel electrode and a second pixel electrode whichare disposed on the unit pixel area and respectively receive differentpixel voltages. The slit portions may be disposed on a plurality ofdomains defined on the first and second pixels, respectively, in thedifferent directions. The common electrode corresponding to the firstand second pixel electrodes may have a substantially flat plate shape inwhich an opening is not disposed. The lower alignment layer and theupper alignment layer may be aligned to be vertically arranged to a longaxis of the liquid crystal molecules when an electric field applied tothe liquid crystal layer is turned off. Alternatively, the loweralignment layer and the upper alignment layer may be aligned to arrangea long axis of the liquid crystal molecules in an extending direction ofthe slit portion at each of the domains when an electric field appliedto the liquid crystal layer is turned off.

An exemplary embodiment provides a method of manufacturing an LCDdevice. In the method, a lower alignment layer is disposed on an arraysubstrate including a pixel electrode including a plurality of slitportions inducing an alignment direction of liquid crystal molecules. Alower reactive mesogen layer is disposed on the lower alignment layer. Aliquid crystal layer is disposed on the lower reactive mesogen layer. Anopposite substrate is coupled with the array substrate. Light isirradiated at a condition in which an electric field is applied to theliquid crystal layer through the pixel electrode to provide a pretiltangle to the liquid crystal molecules at a surface of the lower reactivemesogen layer.

In an exemplary embodiment of the present invention, in the method, anupper alignment layer may be disposed on a common electrode of theopposite substrate before the coupling with the array substrate, and anupper reactive mesogen layer may be disposed on the upper alignmentlayer. The common electrode corresponding to the pixel electrode mayhave a substantially flat plate shape in which an opening is notdisposed.

In an exemplary embodiment of the present invention, the lower reactivemesogen layer and the upper reactive mesogen layer may be formed bycoating a reactive mesogen blend, including a reactive mesogen, on thelower alignment layer and the upper alignment layer, respectively,through a spray method or a coating method. A weight of uncured reactivemesogen material, which is diffused from the lower and upper reactivemesogen layers to the liquid crystal layer, may be no more than about 20weight percent (wt %) with respect to an initial weight of the lower andupper reactive mesogen layer. Alternatively, a weight of uncuredreactive mesogen material, which is diffused from the lower and upperreactive mesogen layers to the liquid crystal layer, may be no more thanabout 1.0 weight percent (wt %) with respect to an initial weight of thelower and upper reactive mesogen layer. A diffusion stop layer may befurther formed, which reduced or effectively prevents the reactivemesogen layer from being diffused to the liquid crystal layer, onsurfaces of the lower reactive mesogen layer and the upper reactivemesogen layer. The diffusion stop layer may be formed through a heatprocessing or a light reactive processing of surfaces of the lowerreactive mesogen layer and the upper reactive mesogen layer before theliquid crystal layer is disposed.

In an exemplary embodiment of the present invention, the lower alignmentlayer and upper alignment layer may be formed by coating a blendincluding at least one of photo-reactive polymer of a cinematic seriesand a polymer of a polyimide series on the pixel electrode and thecommon electrode. The pixel electrodes may be disposed on a unit pixelarea of the array substrate, and the slit portions may be disposed inthe different directions on a plurality of domains defined on each ofthe pixel electrodes. The lower alignment and the upper alignment layermay be aligned so that a long axis of the liquid crystal molecules isvertically aligned. Alternatively, the lower alignment layer and theupper alignment layer may be aligned so that the long axis of the liquidcrystal molecules is arranged in an extending direction of the slitportion at each of the domains.

In exemplary embodiments of the LCD device and the method ofmanufacturing the LCD device, an aperture ratio and a response speed areenhanced, and a generation of an undesired afterimage is decreased, sothat display quality may be advantageously enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detailed exemplaryembodiments thereof with reference to the accompanying drawings, inwhich:

FIG. 1 is a plan view illustrating an exemplary embodiment of an arraysubstrate employed in a liquid crystal display (LCD) device;

FIG. 2 is an equivalent circuit diagram illustrating an exemplaryembodiment of one pixel in the LCD including the array substrateillustrated in FIG. 1;

FIG. 3 is a flowchart illustrating an exemplary embodiment of a methodof manufacturing an LCD device;

FIG. 4 is a cross-sectional view taken along line I-I′ of the arraysubstrate of FIG. 1;

FIG. 5 is a plan view illustrating an exemplary embodiment of the arraysubstrate excluding a pixel electrode of FIG. 1;

FIG. 6 is a plan view illustrating an exemplary embodiment of a pixelelectrode of the array substrate as illustrated in FIG. 1;

FIG. 7 is a cross-sectional view illustrating an exemplary embodiment ofa process for manufacturing a lower alignment layer on an arraysubstrate of FIG. 4;

FIG. 8 is a process diagram illustrating an exemplary embodiment of aprocess for manufacturing a lower reactive mesogen (“RM”) layer on thelower alignment layer through a spray method;

FIG. 9 is a process diagram illustrating an exemplary embodiment of aprocess for manufacturing a lower RM layer on the lower alignment layerthrough a coating method;

FIG. 10 is a cross-sectional view illustrating an exemplary embodimentof a process for manufacturing a lower RM layer on a lower alignmentlayer;

FIG. 11 is a cross-sectional view illustrating an exemplary embodimentof a process for manufacturing a diffusion stop layer on a surface of alower RM layer;

FIG. 12 is a cross-sectional view illustrating an exemplary embodimentof a process for disposing a liquid crystal layer on a lower RM layer;

FIG. 13 is a cross-sectional view illustrating an exemplary embodimentof a process for combining an array substrate including a liquid crystallayer disposed thereon and an opposite substrate;

FIGS. 14 and 15 are cross-sectional views illustrating an exemplaryembodiment of a process for allowing a pretilt angle of liquid crystalmolecules;

FIG. 16 is a cross-sectional view illustrating an exemplary embodimentof a generation of the remaining RM layer in the LCD device, in whichliquid crystals and RM material are blended to form a liquid crystallayer;

FIG. 17 is a graph illustrating a relationship between amounts of the RMremaining in the liquid crystal layer of the LCD device as described inFIG. 16 and an exposing time, and amounts of the RM remaining at theliquid crystal layer of the LCD device as described in FIGS. 1 to 15 andan exposing time;

FIGS. 18A and 18B are cross-sectional views illustrating exemplaryembodiments of a pretilt angle of liquid crystal molecules at a blackdriving area and a white driving area of an LCD device manufactured bythe blending method;

FIGS. 19A and 19B are photographs illustrating exemplary embodiments ofa display screen of the LCD device manufactured by the blending methodas described in FIG. 16; and

FIGS. 20A and 20B are photographs illustrating a display screen of theLCD device as described in FIGS. 1 to 15.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described more fully hereinafter with referenceto the accompanying drawings, in which exemplary embodiments of thepresent invention are shown. The present invention may, however, beembodied in many different forms and should not be construed as limitedto the exemplary embodiments set forth herein. Rather, these exemplaryembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the present invention tothose skilled in the art. In the drawings, the sizes and relative sizesof layers and regions may be exaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. Like numerals refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the present invention.

Spatially relative terms, such as “lower,” “upper” and the like, may beused herein for ease of description to describe one element or feature'srelationship to another element(s) or feature(s) as illustrated in thefigures. It will be understood that the spatially relative terms areintended to encompass different orientations of the device in use oroperation in addition to the orientation depicted in the figures. Forexample, if the device in the figures is turned over, elements describedas “lower” relative to other elements or features would then be oriented“upper” relative to the other elements or features. Thus, the exemplaryterm “lower” can encompass both an orientation of above and below. Thedevice may be otherwise oriented (rotated 90 degrees or at otherorientations) and the spatially relative descriptors used hereininterpreted accordingly.

The terminology used herein is for the purpose of describing particularexemplary embodiments only and is not intended to be limiting of thepresent invention. As used herein, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Exemplary embodiments of the invention are described herein withreference to cross-sectional illustrations that are schematicillustrations of idealized exemplary embodiments (and intermediatestructures) of the present invention. As such, variations from theshapes of the illustrations as a result, for example, of manufacturingtechniques and/or tolerances, are to be expected. Thus, exemplaryembodiments of the present invention should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofthe present invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

All methods described herein can be performed in a suitable order unlessotherwise indicated herein or otherwise clearly contradicted by context.The use of any and all examples, or exemplary language (e.g., “suchas”), is intended merely to better illustrate the invention and does notpose a limitation on the scope of the invention unless otherwiseclaimed. No language in the specification should be construed asindicating any non-claimed element as essential to the practice of theinvention as used herein. Hereinafter, the present invention will beexplained in detail with reference to the accompanying drawings.

FIG. 1 is a plan view illustrating an exemplary embodiment of an arraysubstrate 101 employed in a liquid crystal display (“LCD”) device. FIG.2 is an equivalent circuit diagram illustrating an exemplary embodimentof one pixel PX01 in the LCD including the array substrate 101illustrated in FIG. 1.

Referring to FIGS. 1 and 2, an LCD device includes the array substrate101, an opposite substrate 201 and a liquid crystal layer 180 interposedbetween the array substrate 101 and the opposite substrate 201. Varioustechnologies for enhancing display quality may be employed to the LCDdevice.

In one exemplary embodiment, a plurality of a pixel electrode, indicatedby 162 and 164 in FIGS. 1 and 2, is disposed on a single unit pixel areaPA01 of the LCD device, and receives pixel voltages that are differentfrom each other. A plurality of a micro slit portion, indicated by 161and 165 in FIG. 2, is disposed to extend completely through the pixelelectrodes 162 and 164, respectively, in order to enhance a viewingangle by varying alignment directions of liquid crystal molecules. Areactive mesogen layer is disposed on the pixel electrodes 162 and 164,and a common electrode of the opposite substrate 201, respectively, inorder to enhance a response speed of the liquid crystal. The liquidcrystal is aligned to have a pretilt angle directly by the reactivemesogen layer. The LCD device for enhancing display quality, and amethod of manufacturing the LCD will be described.

In the illustrated embodiment, the array substrate 101 includes, asshown in FIGS. 1 and 2, a plurality of a gate line 111, a plurality of adata line 115, a plurality of a storage line 116, the plurality of pixelelectrodes 162 and 164, and a switching part. In the illustratedembodiment, two pixel electrodes 162 and 164 are disposed on the unitpixel area PA01. A first pixel electrode to which a relatively highlevel pixel voltage is applied may be denoted as a main pixel electrode,and a second pixel electrode to which a relatively low level pixelvoltage is applied may be denoted as a sub-pixel electrode. In theillustrated embodiment of FIGS. 1 and 2, the main pixel electrode isdefined as the first pixel electrode 162, and the sub-pixel electrode isdefined as the second pixel electrode 164.

The first and second pixel electrodes 162 and 164 are each electricallyconnected to a same gate line 111, and are each electrically connectedto different data lines 115. Referring to FIGS. 1 and 2, a pixel of theLCD device is driven in one gate line and two data line (1G2D) method.In the illustrated embodiment, the switching part includes a firstswitching element 122 and a second switching element 124. The firstswitching element 122 electrically connects the first pixel electrode162 to a first gate line 111 and a first data line 115. The secondswitching element 124 electrically connects the second pixel electrode164 to the first gate line 111 and a second data line 115 different fromthe first data line 115, such as an adjacent data line 115.

The storage line 116 includes a first (main) portion longitudinallyextended in the row direction D1, and substantially parallel with thegate lines 111. A plurality of a branch portion is protruded from thefirst portion and extended in the column direction D2 towards the firstswitching element 122 and the second switching element 124 in a planview. A first branch portion 117 and a second branch portion 118 aresubstantially disposed within the unit pixel area PA01, where a portionof each of the first branch portion 117 and the second branch portion118 overlaps with adjacent data lines 115 and the first pixel electrode162. A portion of the first (main) portion of the storage line 116overlaps boundaries of both the first pixel electrode 162 and the secondpixel electrode 164.

The opposite substrate 201 includes a common electrode disposed to facethe first and second pixel electrodes 162 and 164. The first pixelelectrode 162, the common electrode and the liquid crystal layer 180form a first liquid crystal capacitor Clc1, and the second pixelelectrode 164, the common electrode and the liquid crystal layer 180form a second liquid crystal capacitor Clc2. The first pixel electrode162 and a first storage line 116 together form a first storage capacitorCst1, and the second pixel electrode 164 and the first storage line 116together form a second storage capacitor Cst2.

Pixel voltages of the different levels may be applied to the first andsecond pixel electrodes 162 and 164, respectively. In one exemplaryembodiment, a first pixel voltage applied to the first pixel electrode162 is higher than a second pixel voltage applied to the second pixelelectrode 164. Alternatively, a first pixel voltage applied to the firstpixel electrode 162 is lower than a second pixel voltage applied to thesecond pixel electrode 164. When levels of the first and second pixelvoltages are adjusted, images viewed at a side (e.g., not in a front) ofa display screen of the LCD device may have substantially close to orthe same display characteristics of an image viewed at substantially afront of the display screen of the LCD device. Advantageously, displayquality is substantially uniform in accordance with the viewing angle,so that side visibility of the LCD device may be enhanced.

FIG. 3 is a flowchart illustrating an exemplary embodiment of a methodof manufacturing an LCD device.

Summarizing a method of manufacturing the LCD device of the illustratedembodiment, a lower alignment layer is formed on the array substrate 101including a pixel electrode including micro slit portions 161 and 165formed therethrough which determine an alignment direction of liquidcrystal (step S10). A lower reactive mesogen layer is formed on thelower alignment layer (step S20). The liquid crystal layer 180 isdisposed on the lower reactive mesogen (“RM”) layer (step S30). Theopposite substrate 201 is combined with the array substrate 101 (stepS40). In a status in which an electric field is applied to the liquidcrystal layer 180 through the first and second pixel electrodes 162 and164, light is irradiated to the opposite substrate 201 to provide apretilt angle to liquid crystal (step S50).

Hereinafter, each manufacturing processes will be detail described.

FIG. 4 is a cross-sectional view taken along line I-I′ of an arraysubstrate 101 of FIG. 1. FIG. 5 is a plan view illustrating an exemplaryembodiment of an array substrate 101 excluding a pixel electrode ofFIG. 1. FIG. 6 is a plan view illustrating an exemplary embodiment of apixel electrode of an array substrate 101 as illustrated in FIG. 1.

Referring to FIGS. 4, 5 and 6, a lower alignment layer is formed on thearray substrate 101 which includes the first and second pixel electrodes162 and 164 including the micro slit portions 161 and 165, whichdetermine an alignment direction of liquid crystal, formed thereon (stepS10).

The array substrate 101 includes a plurality of a gate line 111, aplurality of a data line 115, first and second switching elements 122and 124 and first and second pixel electrodes 162 and 164 which aredisposed on a lower base substrate 110. In an exemplary embodiment, thelower base substrate 110 may include a glass material, but the inventionis not limited thereto.

A gate metal is coated on the lower base substrate 110 The coated gatemetal is etched to form the gate lines 111. The gate lines 111 aredisposed on the lower base substrate 110 in parallel with a rowdirection D1 indicated in FIGS. 1 and 5. A portion of each of the gatelines 111 forms a gate electrode 112 of a protruding shape. As shown inFIG. 4, a gate insulation layer 121 is disposed on the gate lines 111,and directly contacts both the gate lines 111 and the lower basesubstrate 110.

A semiconductor layer and a source metal layer are sequentially formedon the gate insulation layer 121. The source metal layer and thesemiconductor layer are etched to form a plurality of a data line 115, asource electrode 141, a channel layer 131 and a drain electrode 143 asshown in FIGS. 4 and 5. The data lines 115 are extended in asubstantially column direction D2 indicated in FIG. 5, and disposed onthe gate insulation layer 121. The source electrode 141 is extended fromthe data line 115 at a crossing area of the gate line 111 and the dataline 115, and overlaps with a portion of the gate electrode 112 as shownin FIGS. 4 and 5. A first portion of the drain electrode 143 is disposedon and overlapping the gate electrode 112 at an area overlapping withthe source electrode 141, and a second portion of the drain electrode143 is extended toward and completely overlapped by the unit pixel areaPA01.

Referring to FIGS. 1 and 5, a pair of adjacent gate lines 111 and a pairof adjacent data lines 115 intersect each other to define asubstantially rectangular area therebetween, and the first and secondpixel electrodes 162 and 164 are disposed on the rectangular shapedarea. An entire of both of the first and second electrodes 162 and 164may be disposed between the pair of adjacent gate lines 111 and the pairof adjacent data lines 115. In the illustrated exemplary embodiment, therectangular area will be defined as the unit pixel area PA01, but theinvention is not limited thereto. Alternatively, a shape of the unitpixel area PA01 may be a different shape, such as Z-shape, and/or maynot be defined by gate lines 111 and data lines 115.

Referring again to FIGS. 4 and 5, the gate electrode 112, the gateinsulation layer 121, the channel layer 131, the source electrode 141and the drain electrode 143 define the first switching elements 122, andform a three terminal element. The second switching element 124 mayinclude a gate electrode 114, the gate insulation layer 121, the channellayer 131, a source electrode 142 and a drain electrode 144.

As shown in FIG. 4, the passivation layer 151 covering (e.g.,overlapping) the data line 115 is disposed on the lower base substrate110, and an organic insulation layer 153 is disposed on the passivationlayer 151. A contact hole exposing a portion of the drain electrode 143is extended through both the organic insulation layer 153 and thepassivation layer 151.

An optically transparent and electrically conductive material layer,such as indium tin oxide (“ITO”), indium zinc oxide (“IZO”), amorphousindium tin oxide (“a-ITO”), etc., is disposed on the organic insulationlayer 153, such as by a coating method. The optically transparent andelectrically conductive material layer contacts with the drain electrode143 through the contact hole. The optically transparent and electricallyconductive material layer disposed on the organic insulation layer 153is etched to form the first and second pixel electrodes 162 and 164 asshown in FIGS. 4 and 6. In the illustrated embodiment, in order toenhance a viewing angle, a viewing enhancing technology may be employedin the forming of the first and second pixel electrodes 162 and 164. Inone exemplary, a technology in which an alignment direction of liquidcrystal is divided into a plurality of domains that are different fromeach other may be employed to the unit pixel area PA01.

Referring to the illustrated exemplary embodiment in FIGS. 1 and 6, inorder to obtain the domains, the first and second pixel electrodes 162and 164 may include a plurality of supporting electrodes 163 and 167,and a plurality of micro slit portions 161 and 165, respectively. Thesupporting electrodes 163 and 167 may have substantially a bar shape.The supporting electrodes 163 and 167 may be disposed in a crossed shapedefined by the row direction D1 and the column direction D2, for each ofthe first and second pixel electrodes 162 and 164, respectively.

Each of the supporting electrodes 163 and 167 may include a firstportion longitudinally extending in the row direction D1, and a secondportion longitudinally extending tin the column direction D2. The firstand second portions of each of the first and second pixel electrodes 162and 164 may intersect each other at substantially a 90 degree angle, butthe invention is not limited thereto.

Each of the micro slit portions 161 and 165 may be respectively extendedalong a first oblique line direction D3 (FIGS. 1 and 5) and a secondoblique line direction D4 (FIGS. 1 and 5), which each cross the rowdirection D3 and the column direction D2 with an angle of about 45degrees, respectively. Each of the micro slit portions 161 and 165 maybe formed to extend in different directions by domains be employed tothe unit pixel area PA01.

Each of the micro slit portion 161 and 165 longitudinally extendobliquely with respect to the first and second portions of thesupporting electrodes 163 and 167. In the plan view of FIG. 6,boundaries or edges of the first and second pixel electrodes 162 and 164defined by distal ends of the supporting electrodes 163 and 167 and themicro slit portion 161 and 165 define a substantially rectilinear shape.

Referring to FIGS. 1, 4, 5 and 6, the first pixel electrode 162 mayinclude a first connecting electrode portion 166 protruded from a groupof micro slit portions 161 and overlapping the contact hole extendedthrough both the organic insulation layer 153 and the passivation layer151 which exposes the portion of the drain electrode 143 of the firstswitching element 122. The first connecting electrode portion 166 has aplan view dimension that is larger than both the micro slit portion 161and the supporting electrode 163 portions. The first connectingelectrode portion 166, the micro slit portion 161 and the supportingelectrode 163 portions are electrically connected to each other anddisposed as a single, continuous and indivisible member in the unitpixel area PA01.

Referring to FIGS. 1, 4, 5 and 6, the second pixel electrode 164 mayinclude a second connecting electrode portion 169 protruded from a groupof micro slit portions 165. A first end of the second connectingelectrode portion 169 is continuously disposed with distal ends of thegroup of micro slit portions 165 from which it extends. The secondconnecting electrode portion 169 is longitudinally extended from thegroup of micro slit portions 165 in the column direction D2, andsubstantially parallel with the data lines 115. The second connectingelectrode portion 169 is disposed between a data line 115 and anadjacent border of the first pixel electrode 162, as illustrated in theplan view of FIGS. 1 and 6.

Referring to FIGS. 1, 4, 5 and 6, the second pixel electrode 164 mayfurther include a third connecting electrode portion 168 protruded froma second (e.g., distal) end of the second connecting electrode portion169, and overlapping a contact hole extended through both the organicinsulation layer 153 and the passivation layer 151 which exposes theportion of the drain electrode 144 of the second switching element 124.The second connecting electrode portion 169, the third connectingelectrode portion 168, the micro slit portion 165 and the supportingelectrode 167 portions are electrically connected to each other anddisposed as a single, continuous and indivisible member in the unitpixel area PA01.

A long axis of the liquid crystal may be arranged substantially inparallel with an extended direction of the micro slit portions 161 and165. As a result, a plurality of domains is formed to enhance a viewingangle of the LCD device. A lower polarizing plate (not shown) may beattached at a rear surface (e.g., a lowermost surface in FIG. 4) of thelower base substrate 110.

In one exemplary embodiment, the micro slit portions 161 and 165disposed through the first and second pixel electrodes 162 and 164 maybe obliquely extended in a direction forming at an angle of about 45degrees or about 135 degrees with respect to a lower polarizing axis ofthe lower polarizing plate, such as the first oblique line direction D3and the second oblique line direction D4.

FIG. 7 is a cross-sectional view illustrating an exemplary embodiment ofa process for manufacturing a lower alignment layer 171 on an arraysubstrate 101 of FIG. 4.

Referring to FIG. 7, the lower alignment layer 171 covering the firstand second pixel electrodes 162 and 164 is formed (step S10). The loweralignment layer 171 is disposed overlapping and directly contacting eachof the first and second pixel electrodes 162 and 164, and the organicinsulating layer 153.

In an exemplary embodiment, the lower alignment layer 171 may be formedby coating a photo-reactive polymer of a cinematic series, and a polymerblend of a polyimide series on the first and second pixel electrodes 162and 164 and curing the coated photo-reactive polymer and the polymerblend. In one exemplary embodiment, the photo-reactive polymer of acinematic series and the polymer blend of a polyimide series are blendedin a ratio of about 1:9 (weight percent) to 9:1 (weight percent) to meltin an organic solvent, and then the polymer melted in the organicsolvent is coated on the substrate, such as in a spin coating method.The coated polymer is cured, such as by heating, so that the loweralignment layer 171 may be formed.

An ultraviolet (“UV”) light is irradiated on the lower alignment 171 togenerate an alignment force characteristic for a liquid crystal layer180. By using the light alignment process, the lower alignment layer 171may align liquid crystal of the liquid crystal layer 180 substantiallyin a vertical direction, that is, a direction from the array substrate101 to the opposite substrate 201 which is substantially perpendicularto both the array substrate 101 to the opposite substrate 201.

FIG. 8 is a process diagram illustrating an exemplary embodiment of aprocess for manufacturing a lower RM layer 190 on the lower alignmentlayer 171 through a spray method. FIG. 9 is a process diagramillustrating an exemplary embodiment of a process for manufacturing alower RM layer 190 on the lower alignment layer 171 through a coatingmethod. FIG. 10 is a cross-sectional view illustrating another exemplaryembodiment of a process for manufacturing a lower RM layer 190 on alower alignment layer 171.

Referring to FIG. 3, the lower RM layer 190 is formed on the loweralignment layer 171 (step S20). The lower RM layer 190 may be used toenhance a response speed of the LCD device by allowing a pretilt angleto the liquid crystal layer 180. A term of the “mesogen” is used todefine a light bridge high-molecular copolymer polymer including amesogen group of a liquid crystal property. When a polarized UV light isirradiated to the mesogen, anisotropy of the mesogen is induced, andthen a heat process is performed to enhance a direction property ofliquid crystal.

In the illustrated embodiment, the mesogen group is a polymer materialwhich has a liquid crystal property at a predetermined temperature rangeor a liquid solution state. The reactive mesogen RM may include amaterial or compound including one or more rod-shaped, banana-shaped,board-shaped or disk-shaped mesogenic groups, i.e. groups capable ofshowing liquid crystal phase behavior. The RM may include mesogen havingacrylate, metacrylate, epoxy, oxetanes, vinyl ether, styrene, thiophene,etc.

In one illustrated exemplary embodiment, the mesogen blend RM01including the RM may be coated on the lower alignment layer 171 througha spray method using a spray nozzle SP01 as shown in FIG. 8.Alternatively, as shown in FIG. 9, the mesogen blend RM01 may be coatedon the lower alignment layer 171 through a spin coating method using acoating nozzle NZ01. The mesogen blend RM01 may include a free radicalinitiator having photosensitivity or heat sensitivity, and/or a polymerinitiator such as a cationic agent. The initiator may be operated bylight or heat. The mesogen blend RM01 may include a composition such asat least one of polymer initiators.

After the mesogen blend RM01 is applied to the lower alignment layer 171(FIGS. 8 and 9), a volatile composition is removed from the mesogenblend RM01, and the lower RM layer 190 is formed on the lower alignmentlayer 171 as shown in FIG. 10. The lower RM layer 190 may be disposed onessentially a whole of the array substrate 101, and overlapping anddirectly contacting the organic insulating layer 153.

When liquid crystal is arranged on the lower alignment layer 171, thelower RM layer 190 is aligned in an alignment direction of the loweralignment layer 171 to induce the liquid crystal to have a pretiltangle. In order not to cure the lower RM layer 190, an incident lightprovided from an external side may be blocked to the lower RM layer 190during the spray process or the spin coating process.

FIG. 11 is a cross-sectional view illustrating an exemplary embodimentof a process for manufacturing a diffusion stop layer on a surface of alower RM layer 190.

In the method of manufacturing the LCD device, a liquid crystal layer180 is disposed on the lower RM layer 190. Since the lower RM layer 190is not cured when the liquid crystal layer 180 is disposed on the lowerRM layer, the RM in the lower RM layer 190 may be distributed to theliquid crystal layer 180. When an amount of RM mixed to the liquidcrystal layer 180 is relatively large, a generation of an undesirableafterimage may be increased in an LCD device. Referring to FIG. 11, adiffusion stop layer (not shown) may be formed on the lower RM layer190, in order to suppress the RM in the lower RM layer 190 from beingtransferred into the liquid crystal layer 180. In an exemplaryembodiment, the diffusion stop layer is a relatively thin film intowhich characteristics of a surface of the lower RM layer 190 are varied.The diffusion stop layer is disposed between the lower RM layer 190 andthe liquid crystal layer 180.

In one exemplary embodiment, a UV light of which strength and time areproperly controlled, is irradiated to a surface of the lower RM layer190 (as indicated by H01 in FIG. 11) to soft light cure the surface ofthe lower RM layer 190, so that the diffusion stop layer may be formed.Alternatively, an infrared ray of which strength and time are properlycontrolled is irradiated to a surface of the lower RM layer 190 to softheat cure the surface of the lower RM layer 190, so that the diffusionstop layer may be formed.

In an alternative embodiment, when adhesive characteristics between thelower RM layer 190 and the lower alignment layer 171, and chemicalcomposition of the RM are properly controlled and selected, the amountof the RM disposed in the liquid crystal layer 180 may be decreased eventhough the diffusion strop layer is not formed. Therefore, a formationprocess of the diffusion stop layer may be omitted.

FIG. 12 is a cross-sectional view illustrating an exemplary embodimentof a process for disposing a liquid crystal layer 180 on a lower RMlayer 190.

A liquid crystal layer 180 is disposed on the lower RM layer 190 asshown in FIG. 12, after the formation process of the diffusion stoplayer or after the formation process of the lower RM layer 190 (stepS30). Liquid crystals 181 are disposed on the lower RM layer 190, suchas through a direct drop method, so that the liquid crystal layer 180may be disposed on the lower RM layer 190.

FIG. 13 is a cross-sectional view illustrating an exemplary embodimentof a process for combining an array substrate 101 including a liquidcrystal layer 180 disposed thereon, and an opposite substrate 201.

As shown in FIG. 13, the opposite substrate 201 is combined with thearray substrate 101 (step S40).

The opposite substrate 201 may include an upper base substrate 210, alight-blocking pattern 221, a color filter pattern 231, an overcoatinglayer 241, a common electrode 251 and an upper alignment layer 261.

The light-blocking pattern 221 is disposed on the upper base substrate210 in correspondence with (e.g., overlapped with portions of) the gateline 111, the data line 115, the first and second switching elements 122and 124 and the storage line 116. The light-blocking pattern 221 may anot be disposed overlapping the unit pixel area PA01. The color filterpattern 231 is disposed on the unit pixel area PA01 which is not blockedby light. In an exemplary embodiment, the color filter pattern 231 mayinclude, but is not limited to, a red color filter, a green color filterand a blue color filter. The red, green and blue color filters may besequentially disposed in correspondence with each unit pixel area PA01in a column direction D1.

The overcoating layer 241 overlaps the color filter pattern 231 and thelight-blocking pattern 221, such being disposed on an entire of theupper base substrate 210. The common electrode 251 is disposed on theovercoating layer 241 and opposite to the upper base substrate 210 withrespect to the overcoating layer 241. In the illustrated embodiment, amaterial of the common electrode 251 is same as that of the first andsecond pixel electrodes 162 and 164.

Where the common electrode 251 is disposed corresponding substantiallyto the unit pixel area PA01, the common electrode 251 may be formed in asubstantially flat plate shape in which slit portions, that is, anopening is not formed. The common electrode 251 may be disposed as asingle, continuous and indivisible member as including no openings. Inthe illustrated embodiment, when micro slit portions 161 and 165 areformed in the first and second pixel electrodes 162 and 164,respectively, and the common electrode 251 is formed in a substantiallycontinuous flat plate shape in which slit portions are not formed, aliquid crystal cell type is called as a super-vertical alignment(“S-VA”) mode. Alternatively, the liquid crystal layer 180 may be drivenin a pattern vertical alignment (“PVA”) mode. In the PVA mode, aplurality of slit portions for forming a fringe field on each of thefirst pixel electrode 162, the second pixel electrode 164 and the commonelectrode 251 may be disposed.

Referring again to FIG. 13, the upper alignment layer 261 is disposed onthe common electrode 251. In an exemplary embodiment, a material of theupper alignment layer 261 is same as that of the lower alignment layer171.

An upper RM layer 290 may be disposed on the upper alignment layer 261by using the same method if forming the lower RM layer 190, that is, thespray method or the coating method as described above.

In an exemplary embodiment, an upper polarizing plate (not shown) may bedisposed on an outer surface of the opposite substrate 201, such as toform an outermost layer of the LCD device. A polarizing axis of theupper polarizing plate may be substantially perpendicular to that of thelower polarizing plate.

Prior to applying an electric field between the first and second pixelelectrodes 162 and 164 of the array substrate 101, and the commonelectrode 251 of the opposite substrate 201, a long axis direction ofliquid crystal 181 (hereinafter, referred to as a director of liquidcrystal) may be aligned in a direction substantially perpendicular tothe array substrate 101 and the opposite substrate 201 as shown in FIG.13.

FIGS. 14 and 15 are cross-sectional views illustrating an exemplaryembodiment of a process for allowing a pretilt angle of liquid crystalmolecules 181.

Referring to FIGS. 14 and 15, light 7 is irradiated to the liquidcrystal layer 180 through the opposite substrate 201 to affect a pretiltangle to the liquid crystal 181 at a surface of the lower RM layer 190and a surface of the upper RM layer 290 (step S50).

When the pixel voltage is applied to the first and second pixelelectrodes 162 and 164, and when the common voltage is applied to thecommon electrode 251, the director of the liquid crystal 181 is alignedin substantially a horizontal direction as shown in FIG. 14. Thus, awhite driving mode may be realized. In exemplary embodiments, in orderto fully align the director of the liquid crystal 181, the pixel voltageand the common voltage may be increased.

In the white driving mode, as shown in FIG. 14, an ultraviolet light 7is irradiated on the opposite substrate 201. The lower RM layer 190 andthe upper RM layer 290 are cured at surfaces of the lower RM layer 190and the upper RM layer 290 adjacent to the lower and upper alignmentlayers 171 and 261, respectively, to determine a direction property ofliquid crystal 181 in response to the ultraviolet light.

Referring to FIG. 15, the liquid crystals 181 a and 181 b directlyadjacent to the lower and upper RM layers 190 and 290, respectively, maybe substantially fixed in a direction in which the liquid crystals 181 aand 181 b are arranged in the horizontal direction. When an electricfield is not applied to the liquid crystal layer 180, as shown in FIG.15, liquid crystals are arranged. That is, liquid crystals 181 a and 181b horizontally lie down at surfaces of the lower RM layer 190 and theupper RM layer 290 adjacent to the liquid crystal layer 180, or have aninclined angle with respect to surfaces of the lower RM layer 190 andthe upper RM layer 290. For the liquid crystals located closer to amiddle of liquid crystal layer between the array substrate 101 and theopposite substrate 201, the liquid crystals 181 c are gradually arrangedsubstantially perpendicular with respect to surfaces of the lower RMlayer 190 and the upper RM layer 290 as a distance increases from thearray substrate 101 and the opposite substrate 201.

Due to the arrangement of the liquid crystal 181, a response time of theliquid crystal 181 may be advantageously enhanced. Moreover, arrangementdirections of the liquid crystal are various, so that a viewing anglemay be advantageously enhanced.

In the illustrated embodiment, the RM of the lower and upper RM layers190 and 290 are not mixed with the liquid crystal 181 to be curedthrough a UV light, at a condition in which the RM is coated on surfacesof the lower alignment layer 171 and the upper alignment layer 261.Advantageously, as described above, the RM is not mixed with the liquidcrystal layer 180.

FIG. 16 is a cross-sectional view illustrating an exemplary embodimentof a generation of a remaining reactive mesogen layer in the LCD devicewhich liquid crystals and reactive mesogen material are blended to forma liquid crystal layer 580. in FIG. 16, a hatched pattern represents aliquid crystal molecule, and a non-hatched pattern represents a reactivemesogen.

Referring to FIG. 16, different from the previously illustratedembodiment, instead of forming a RM layer by coating the reactivemesogen on a lower alignment layer 571 and an upper alignment layer 661,a light curing process may be performed at a mixture state of the RMinto the liquid crystal layer 580. The light curing method for the RMwill be designated as a “blend method,” and the light curing method forthe RM such as described for the previously illustrated embodiment willbe designated as a “coating method” or “deposition method.”

According to the blend method, as shown in FIG. 16, the reactive mesogenRM04 disposed at a relatively far distance from the lower alignmentlayer 571 and the upper alignment layer 661 is influenced by the loweralignment layer 571 and the upper alignment layer 661, rather thanreactive mesogens RM02 and RM03 adjacent to and disposed closer to thelower alignment layer 571 and the upper alignment layer 661,respectively. In a manufacturing process, the adjacent reactive mesogensRM02 and RM03 are cured at a surface of the lower alignment layer 571and the upper alignment layer 661 to form a lower RM layer 590 and anupper RM layer 690, respectively. However, the reactive mesogen RM04disposed further from the lower alignment layer 571 and the upperalignment layer 661 is not cured, and remains in the liquid crystallayer 580.

An undesirable decreasing amount of liquid crystal alignment capabilitydue to the remaining reactive mesogen RM04 in the liquid crystal layer580, is called as an alignment losing ratio. The alignment losing ratiodepends upon not only characteristics of liquid crystal composition suchas elasticity and viscosity, but also depends upon a chemicalcomposition of the lower alignment layer 571 and the upper alignmentlayer 661, and characteristics of pattern formed on an alignment layer.

FIG. 17 is a graph illustrating a relationship between an amount of theRM which is remaining in the liquid crystal layer 580 of the LCD deviceas described in FIG. 16 (blend method) and an exposing time, and anamount of the RM which is remaining in the liquid crystal layer of theLCD device as described in FIGS. 1 to 15 (deposition method) and anexposing time.

In FIG. 17, a horizontal axis represents an exposing strength (J/cm²) ofa UV light used to a light curing process for the RM, and a verticalaxis represents a mass ratio of RM amount which is not cured after alight curing process and remains within the liquid crystal layer 580with respect to a mass of an initially inputted RM. The RM remainingamount corresponding to the blend method (FIG. 16) is based on an amountof mixture RM of the liquid crystal layer 580, and the RM remainingamount corresponding to a coating method (FIGS. 1-15) is based on anamount of RM included in the lower RM layer 190 and the upper RM layer290.

As shown in FIG. 17, observing the graph of the RM remaining amount ofthe blend method of FIG. 16, the RM remaining amount is graduallydecreased as a time increases, such as shown that the RM remainingamount is close to about 35 weight percent (wt %). That is, even thoughan exposing time is relatively long, it is recognized the RM remainingamount decreases close to a uniform threshold value, that is, the RMremaining amount does not continuously decrease.

When observing the graph of RM remaining amount of a coating method ofFIGS. 7-15, the RM remaining amount is about 15 wt % initially, and itis shown that the RM remaining amount is maintained to be about 12 wt %after the coating process is completed. That is, the RM is diffused intothe liquid crystal layer 180 through the coating method, however, the RMremaining amount is about ⅓ of the blend method. Thus, in the coatingmethod, the decreasing of display quality due to the remaining reactivemesogen RM04 may be reduced or effectively prevented since the RMremaining amount is about ⅓ of the blend method.

An LCD structure including a remaining amount of reactive mesogen in theliquid crystal layer may be formed using an exemplary embodiment of thelight curing method for the RM, designated as a “blend method,” and anexemplary embodiments of the light curing method for the RM designatedas a “coating method” or “deposition method.” The remaining amount ofreactive mesogen in the liquid crystal layer is considered as adistinctive structural characteristic of the LCD.

Since the remaining amount of reactive mesogen in the liquid crystallayer is imparted by forming a reactive mesogen layer on an alignmentlayer of a first substrate, disposing a liquid crystal layer on thelower alignment layer, combining the first substrate with a secondsubstrate and irradiating the combined substrates to generate a pretiltangle in the liquid crystal layer of the coating method, such a processis considered as imparting the distinct structural characteristic of theremaining amount of reactive mesogen in the liquid crystal layer.Additionally, since the remaining amount of reactive mesogen in theliquid crystal layer is imparted by form a reactive mesogen layerthrough coating a mixture of the reactive mesogen and liquid crystal ona lower alignment layer and an upper alignment layer, and light curingthe mixture state of the RM into the liquid crystal layer, such aprocess is also considered as imparting the distinct structuralcharacteristic of the remaining amount of reactive mesogen in the liquidcrystal layer.

FIGS. 18A and 18B are cross-sectional views illustrating an exemplaryembodiment of a pretilt angle of liquid crystal molecules at a blackdriving area B01 and a white driving area W01, of an LCD devicemanufactured by the blending method as described in FIG. 16.

Referring to FIGS. 18A and 18B, the liquid crystal 581 is substantiallyvertically aligned and backlight (indicated by the upward arrows) isblocked at a black driving area B01 of the LCD device manufactured bythe blend method, so that black is displayed. The liquid crystal 581 issubstantially horizontally aligned and backlight is transmitted at awhite driving area W01 of the LCD device manufactured by the blendmethod, so that white is displayed. In the blend method, the remainingRM RM04 of the liquid crystal layer 580 responds to the backlight BL01during the black driving and the white driving, and then the remainingRM RM04 is additionally cured at a surface of the lower RM layer 590 andthe upper RM layer 690. Accordingly, a pretilt angle of the liquidcrystal 581 is altered at a surface of the lower RM layer 590 and theupper RM layer 690.

Additional curing amounts of the RM are different from each other at theblack driving area B01 and the white driving area W01. Thus, as shown inFIG. 18B, when an electric field is turned off, that is, even though atotal display screen is displayed in black, pretilt angles of the liquidcrystal 581 may be different from each other at the black driving areaB01 and areas which were the white driving area W01.

FIGS. 19A and 19B are photographs illustrating an exemplary embodimentof a display screen of the LCD device manufactured by the blendingmethod as described in FIG. 16. FIG. 19A shows a display screen that isobserved when a total display screen is displayed in black after thewhite driving area W01 is driven in about 220-gray with respect to theblack driving area B01 for about 24 hours at a peripheral temperature ofabout 50 Celsius degrees. FIG. 19B shows a display screen that isobserved when a total display screen is displayed in black after thewhite driving area W01 is driven in about 245-gray with respect to theblack driving area B01 for about 168 hours at a peripheral temperatureof about 50 Celsius degrees.

Referring to FIGS. 19A and 19B, in the aforementioned blend method,pretilt angles of the liquid crystal 581 are different from each otherin accordance with the black driving area B01 and the white driving areaW01, so that a gradation displayed at a black status may be differentfrom each other in accordance with areas and lapse time. Therefore, anundesirable afterimage may be clearly observed on the display screen.That is, display quality may be greatly decreased.

FIGS. 20A and 20B are photographs illustrating a display screen of theLCD device as described in FIGS. 1 to 15. FIG. 20A shows a displayscreen that is observed when a total display screen is displayed inblack after the white driving area W01 is driven in about 90-gray withrespect to the black driving area B01 for about 24 hours at a peripheraltemperature of about 50 Celsius degrees. FIG. 20B shows a display screenthat is observed when a total display screen is displayed in black afterthe white driving area W01 is driven in about 180-gray to about 200-graywith respect to the black driving area B01 for about 168 hours at aperipheral temperature of about 50 Celsius degrees.

Referring to FIGS. 20A and 20B, the remaining RM RM04 within the liquidcrystal layer 180 is decreased in a coating method such as the presentembodiment, so that an additional curing of the reactive mesogen due tothe backlight BL01 at the black driving area B01 and the white drivingarea W01 while an LCD device is driven is not generated. Thus, thepretilt angle of the liquid crystal 181 may be uniform in accordancewith areas. As a result, it is recognized that an afterimage is notviewed even though a lapse time is about 168 hours as shown in FIG. 20B.

According to exemplary embodiment of an LCD device and a method ofmanufacturing the LCD device, in an LCD device which allows a pretiltangle by using a reactive mesogen, the remaining reactive mesogenremaining within a liquid crystal layer may be decreased.Advantageously, an afterimage due to the remaining reactive mesogen in adisplay screen may be removed, so that display quality may be enhanced.Therefore, the illustrated embodiments may be adapted to an LCD deviceusing a reactive mesogen.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although exemplary embodiments of thepresent invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of the present invention. Accordingly, all such modificationsare intended to be included within the scope of the present invention asdefined in the claims. In the claims, means-plus-function clauses areintended to cover the structures described herein as performing therecited function and not only structural equivalents but also equivalentstructures. Therefore, it is to be understood that the foregoing isillustrative of the present invention and is not to be construed aslimited to the specific exemplary embodiments disclosed, and thatmodifications to the disclosed exemplary embodiments, as well as otherexemplary embodiments, are intended to be included within the scope ofthe appended claims. The present invention is defined by the followingclaims, with equivalents of the claims to be included therein.

1. A liquid crystal display device comprising: an array substratecomprising: a lower substrate including a switching part disposedthereon; a pixel electrode disposed on a unit pixel area of the lowersubstrate and contacting the switching part, the pixel electrodeincluding a plurality of a slit portion disposed on a plurality ofdomains and extended in different directions; and a lower reactivemesogen layer disposed on the pixel electrode to induce an inclineddirection of liquid crystal molecules; an opposite substrate comprisingan upper substrate disposed facing the lower substrate of the arraysubstrate, a common electrode disposed on the upper substrate and facingthe pixel electrode, and an upper reactive mesogen layer disposed on thecommon electrode; and a liquid crystal layer comprising the liquidcrystal molecules having a pretilt angle between an inner surface of thelower reactive mesogen layer and an inner surface of the upper reactivemesogen layer.
 2. The LCD device of claim 1, wherein the array substratefurther comprises a lower alignment layer disposed between the pixelelectrode and the lower reactive mesogen layer, and the oppositesubstrate further comprises an upper alignment layer disposed betweenthe common electrode and the upper reactive mesogen layer.
 3. The LCDdevice of claim 2, wherein a weight of reactive mesogen material of thelower and upper reactive mesogen layers remaining in the liquid crystallayer, is no more than about 20 weight percent (wt %) with respect to aweight of the lower and upper reactive mesogen layers.
 4. The LCD deviceof claim 3, further comprising: a diffusion stop layer disposed on theinner surfaces of the lower reactive mesogen layer and the upperreactive mesogen layer to block the lower reactive mesogen layer and theupper reactive mesogen layer from being diffused to the liquid crystallayer.
 5. The LCD device of claim 2, wherein the pixel electrodecomprises a first pixel electrode and a second pixel electrode which aredisposed on the unit pixel area to respectively receive different pixelvoltages, and the slit portions are disposed on a plurality of domainsof the first and second pixels, respectively, in the differentdirections.
 6. The LCD device of claim 5, wherein the common electrodedisposed facing the first and second pixel electrodes has asubstantially flat plate shape in which an opening is not disposed. 7.The LCD device of claim 5, wherein the lower alignment layer and theupper alignment layer are aligned to vertically arrange a long axis ofthe liquid crystal molecules when an electric field applied to theliquid crystal layer is turned off.
 8. The LCD device of claim 5,wherein the lower alignment layer and the upper alignment layer arealigned to arrange a long axis of the liquid crystal molecules in anextending direction of the slit portion at each of the domains when anelectric field applied to the liquid crystal layer is turned off.
 9. Amethod of manufacturing a liquid crystal display device, the methodcomprising: forming a lower alignment layer on an array substratecomprising a pixel electrode including a plurality of slit portionsinducing an alignment direction of liquid crystal molecules; forming alower reactive mesogen layer on the lower alignment layer; disposing aliquid crystal layer on the lower reactive mesogen layer; coupling anopposite substrate with the array substrate; and irradiating light at acondition in which an electric field is applied to the liquid crystallayer through the pixel electrode to provide a pretilt angle to liquidcrystal molecules at a surface of the lower reactive mesogen layer. 10.The method of claim 9, further comprising: forming an upper alignmentlayer on a common electrode of the opposite substrate before theopposite substrate is coupled with the array substrate; and forming anupper reactive mesogen layer on the upper alignment layer.
 11. Themethod of claim 10, wherein the common electrode is disposed facing thepixel electrode and has a substantially flat plate shape in which anopening is not formed.
 12. The method of claim 10, wherein forming thelower reactive mesogen layer and forming the upper reactive mesogenlayer comprise: coating a reactive mesogen blend including a reactivemesogen material on the lower alignment layer and the upper alignmentlayer, respectively, through a spray method or a coating method.
 13. Themethod of claim 12, wherein a weight of uncured reactive mesogenmaterial, which is diffused from the lower and upper reactive mesogenlayers to the liquid crystal layer, is no more than about 20 weightpercent (wt %) with respect to an initial weight of the lower and upperreactive mesogen layer.
 14. The method of claim 12, wherein a weight ofuncured reactive mesogen material, which is diffused from the lower andupper reactive mesogen layers to the liquid crystal layer, is no morethan about 1.0 weight percent (wt %) with respect to an initial weightof the lower and upper reactive mesogen layer.
 15. The method of claim14, further comprising: forming a diffusion stop layer to block thereactive mesogen layer from being diffused to the liquid crystal layeron inner surfaces of the lower reactive mesogen layer and the upperreactive mesogen layer, the forming the diffusion layer includes heatprocessing or a light reactive processing the inner surfaces of thelower reactive mesogen layer and the upper reactive mesogen layer beforethe liquid crystal layer is disposed.
 16. The method of claim 10,wherein the forming the lower alignment layer and the upper alignmentlayer comprises: coating a blend including at least one ofphoto-reactive polymer of a cinematic series and a polymer of apolyimide series on the pixel electrode and the common electrode. 17.The method of claim 16, wherein the pixel electrode comprises a firstpixel electrode and a second pixel electrode, the first pixel electrodeand the second pixel electrode formed on a unit pixel area of the arraysubstrate, and the slit portions are formed in different directions on aplurality of domains defined on each of the first and second pixelelectrodes.
 18. The method of claim 17, wherein the lower alignment andthe upper alignment layer are aligned so that a long axis of the liquidcrystal molecules is vertically aligned.
 19. The method of claim 17,wherein the lower alignment layer and the upper alignment layer arealigned so that the long axis of the liquid crystal molecules isarranged in an extending direction of the slit portion at each of thedomains.